In Genesis, what was the Ark's only stated opening for entry?

In Genesis, the Ark's stated entry opening was a door in its side.

Genesis 6:16 instructs Noah to make a door in the side of the ark. The same verse mentions a window and three levels, but it distinguishes the door from the window. Genesis 7:16 later says that Noah and the animals entered, and that the Lord shut the door behind them.

The text does not describe a front gate, ramp, or roof hatch as the entrance. Artistic reconstructions often add features needed for a practical modern ship, but those details are not specified in Genesis. The door’s position is one of the few architectural features given alongside the vessel’s dimensions, rooms, decks, and waterproof coating.